I would try to narrow the search down. I am not familiar with the routing of the wires on that particular vehicle so you will need to do a little looking around. The wires usually run through the trunk to the back of the lights. Have you hauled something in the trunk recently that could have cut or unplugged the wires? This time of the year people are trying to shove all kinds of things in the trunk; presents, trees, etc.. If you have been hauling stuff I think that would be the first place that I would look.

While looking, inspect & clean any grounds that you may find, inspect & clean any connections, and use a test light to check for power and ground. In most cases the backs of the lights are accessible from the trunk compartment. Check to make sure the back of the lights didn't get broke from something being hauled in the trunk.

Garner is spot on. Having worked on those cars brand new I've seen a few cars with this issue. Make sure to check for the most obvious things first. Make sure the bulbs and fuses are all good. I have seen entire rear sets of bulbs blow out before without any other electrical issues. If you can't tell right away, a multimeter can help check continuity. If bulbs and fuses are fine then I suggest finding a wiring diagram and start chasing wires. Also, as Garner mentioned, find all of the grounds and clean them thoroughly. I always found a good piece of scuff pad would do the job just fine, but if you don't have scuff pad use some sandpaper (100 grit works).

Auto Mechanics World - THE place to go if you are interested in getting into the automotive service industry.